1. Field of the Invention
The present invention relates generally to a wheelchair, and more particularly to a power wheel, which may drive on a rough road.
2. Description of the Related Art
A conventional power wheelchair has a frame, on which two front wheels, two driving wheels and two rear wheels are provided on a front, middle and rear thereof respectively. The frame also is provided with two front wheel mounts and two driving wheel mounts on left and right sides to pivot the front wheels and the driving wheels thereon respectively. However, the front wheel mounts and the driving wheel mounts are rigid bodies and made in an integral with the frame, so that the wheelchair is hard to drive on a rough road. To overcome above problem, some had provided the front wheel mounts and the driving wheel mounts independently pivoted on the frame with a distance therebetween and two coupling assemblies connecting the front wheel mounts and the driving wheel mounts respectively. The front wheel mounts and the driving wheel mounts may be moved relatively to the frame independently and the coupling assemblies provide connections between the front wheel mounts and the driving wheel mounts to make the front wheels and the driving wheels keep in touch on the ground to stabilize the wheelchair. In addition, there are cushion devices between the front and driving wheel mounts and the frame to absorb vibration that make user sit on the wheelchair more comfortable.
However, the coupling assemblies, which connect the front wheel mounts and the driving wheel mounts to keep them in touch on the ground, usually are very complex. Typically, the coupling assembly is a multi-linkage mechanism including a plurality of links with various lengths. This kind of multi-linkage mechanism is hard to design and assemble and has a high cost. Furthermore, stress always concentrates at pivots between the links that means the coupling assembly cannot work for a long time. Again, the cushion devices are adjacent to a seat of the wheelchair that vibration transmits to the seat through the cushion devices. As a result, the user is not comfortable to sit on the wheelchair and the cushion capacity of the wheelchair is limited also.